Glenn Zimmermann's Long Range Fall Outlook

September

I just need to say this: it’s been a weird September so far. Normally, the first couple of weeks are kind of hot and humid. And it’s not until about the third week that we see a cooldown into a fall mode. This year, the cool rolled in late August, and we had a good run of below normal temperatures. Then, second summer and 90s. So, the month has kind of flip-flopped just a bit. But a back-to-average trend will work us through the end of the month.

Last September began cooler, with the heat building through the month. We hit 96 degrees on the 20th.

This year, after the fall feel, then second summer, we get back to average temps.

Last September was dry to start, then we had some big rain late in the game that made for an above normal monthly total.

October

This year, October is a true transition month. We are in between a summer pattern that got hot and dry, and we are going to a winter pattern that may not be that dry. Let’s watch the tropics, and especially the Gulf of Mexico, for developing systems late in the season. That could dictate the overall rain total. But on the whole, October is very dry with only a few chances for rain all month long.

By this time of the year, we are waiting for the end of the growing season with the average first freeze toward the end of the month. With warmer-than-normal trends on the way, any frost or freeze may be delayed all the way until November. Cooler nights will start the leaf change cycle, but that will also be delayed because of the warmer-than-normal trends.

Last year, October was warm with highs in the 80s, all the way until the end of the month.

This October trends warmer than normal, but not that warm. Think more 70s than 60s for highs. Last October was very dry — two inches short for the month. This October could be pretty close to that, with only a few chances of rain.

November

Full disclosure: November is a hard month to forecast. Sometimes it’s more fall than winter, and sometimes it’s more winter than fall. In the last few years, we have had some snow in the month.

This year, the signs are something different altogether. There will be multiple chances of precipitation all month long, and I think we will emerge with an above normal monthly total. In fact, we could see one to two chances each week of the month. That’s a fast developing La Niña spike for the month.

The big question is how will the temperature trends look. That is always a tough call for a November. But this year with above normal trends, it looks like mostly these are rain events, and not snow events. As always, let’s watch the end of the month, and especially around Thanksgiving for any shots of cold. And then there’s this: it appears that this may be a precipitation trend that builds through December and January, but we will save that for our winter outlook in November.

Do you remember last November? Nine-plus inches of rain and 3.2 inches of snow on the 30th! A wild month.

This November will also trend wet, but not white with an active pattern emerging quickly.

Last November had an above normal temperature trend and we didn’t hit the first freeze of the fall until late in November.

This year, with more rain chances on the way, we will trend cool with very few wild temperature swings. The first freeze will be early in the month.